Diphenylalkanes are useful materials of commerce in that they are used as secondary plasticizers. In order to be used it is necessary that they have very little color. Typically, the material of commerce will have a light yellow or yellow color. Unfortunately, under some conditions, the product turns to a green color which renders it unsuitable for use as a secondary plasticizer.
We have found a method of preventing, or substantially reducing, this color deterioration of diphenylalkanes. Briefly, the method comprises contacting the diphenylalkanes with an effective amount of ammonia or certain amines.